Primer on gypsum board

Hello,

I have installed a suspended plasterboard ceiling in the basement (Rigips green, the impregnated ones).

Now I have treated it with Murexin LF14 (diluted 1:1 with water) using a broad brush/primer brush in the first rooms. Felt more on the floor than on the ceiling :). In the other rooms, I also applied Murexin LF14 (however diluted 1:2 with water) using a roller.

My question is, how often do you have to treat the plasterboard with it, and how much/how thoroughly should it be applied?
Is it enough if the boards shine under the spotlight after application?

Should more be applied in the area where a sauna will be installed later?

Thanks for your help!

The primer has the task of equalizing the absorbency between the cardboard and the filler and acting as an adhesion promoter. So if it shines, it is definitely enough. The sauna will surely be installed additionally, so the absorbency of the gypsum board has nothing to do with this. Regards